A new analysis of scientific research found that vitamin B3 may lower your risk of the most common type of cancer in the U.S. Researchers found that people who took vitamin B3 twice a day for at least 30 days had 14 percent fewer new skin cancers. The findings don’t suggest that everyone should start taking a B3 supplement, but they do raise some questions about this vitamin’s role in reducing skin cancer risk. Vitamin B3 is a water-soluble vitamin. There are a few ways B3 may help lower the risk of skin cancer.